Merge pull request #61 from soldair/master

adding entity.abort() to stop writes from the parser

Author: soldair

lib/entry.js

@@ -24,6 +24,7 @@ function Entry (header, extended, global) {
   this._ending = false
   this._ended = false
   this._remaining = 0
+  this._abort = false
   this._queue = []
   this._index = 0
   this._queueLen = 0
@@ -209,5 +210,11 @@ Entry.prototype._setProps = function () {
   this._remaining = props.size
 }
 
+// the parser may not call write if _abort is true. 
+// useful for skipping data from some files quickly.
+Entry.prototype.abort = function(){
+  this._abort = true
+}
+
 Entry.prototype.warn = fstream.warn
 Entry.prototype.error = fstream.error

lib/parse.js

@@ -102,7 +102,11 @@ Parse.prototype._process = function (c) {
 
   if (this._entry) {
     var entry = this._entry
-    entry.write(c)
+    if(!entry._abort) entry.write(c)
+    else {
+      entry._remaining -= c.length
+      if(entry._remaining < 0) entry._remaining = 0
+    }
     if (entry._remaining === 0) {
       entry.end()
       this._entry = null

test/parse-discard.js

@@ -0,0 +1,29 @@
+var tap = require("tap")
+  , tar = require("../tar.js")
+  , fs = require("fs")
+  , path = require("path")
+  , file = path.resolve(__dirname, "fixtures/c.tar")
+
+tap.test("parser test", function (t) {
+  var parser = tar.Parse()
+  var total = 0
+  var dataTotal = 0
+
+  parser.on("end", function () {
+
+    t.equals(total-513,dataTotal,'should have discarded only c.txt')
+
+    t.end()
+  })
+
+  fs.createReadStream(file)
+    .pipe(parser)
+    .on('entry',function(entry){
+      if(entry.path === 'c.txt') entry.abort()
+      
+      total += entry.size;
+      entry.on('data',function(data){
+        dataTotal += data.length        
+      })
+    })
+})